电流对人体的效应由生理参数和电气参数决定。15~100Hz正弦交流电流反应阈的通用值为()。
A.1.5mA
B.2mA
C.0.1mA
D.0.5mA
参考答案:D
公路旁每两根电线杆之间的距离是15米,小明从第一根电线杆跑到第10根电线杆,共跑了多少米?
— Are you content with her lecture?
— Nowhere near that. It ____. [ ]
A. may have been good
B. couldn't have been worse
C. can't be better
D. must be better